Cambridge IGCSE Biology - 0610 - Core Paper 3 2015 Summer Zone 2

Fig. 1.1 shows three vertebrates. Each is from a different class (group) of vertebrate.

(a) State one characteristic of all vertebrates.
..............................................................................................................................[1]

(b) (i) Name the two other classes of vertebrate not shown in Fig. 1.1.
1 ........................................................................................................................................
2 ........................................................................................................................................[2]

(ii) Name the feature which covers the surface of the bodies of animals in these two classes but not the three animals shown in Fig. 1.1.
..............................................................................................................................[1]

(a) Complete the following paragraph about enzymes. Choose words from this list. Use each word only once or not at all.
activators catalysts enzymes
protein reactions unusual

All enzymes are made of .......................................................... molecules. They control the metabolic .................................................. in living organisms. The enzymes act as ....................................................... as they speed up processes but are not permanently changed. [3]

(b) Enzymes are important in chemical digestion.
Define the term digestion.
.................................................................................................................................................................................................
.................................................................................................................................................................................................
.................................................................................................................................................................................................
.................................................................................................................................................................................................
................................................................................................................................................................................................. [2]

(c) In an investigation to measure the effect of pH on enzyme activity, a protease enzyme was mixed with solutions of different pH values. The mixtures were placed in holes cut in the centre of dishes of gelatin.
Gelatin is a protein which can be stained with a coloured dye. When the protease digests the gelatin a colourless zone forms.

Fig. 2.1 shows a dish at the start of the experiment. Fig. 2.2 shows the dishes after a period of 24 hours.



(i) Using Fig. 2.2, state the optimum (best) pH for the activity of this protease. .................. [1]

(ii) Suggest the region of the alimentary canal in which this protease carries out its function.
................................................................................................................................................................................................. [1]

(iii) Complete the equation to explain how the protease caused the colourless zones to appear.
protease ............................................................ → ............................................................ [2]

(d) The experiment was carried out at 20°C.
Suggest what would happen if the experiment was carried out at 30°C.
.................................................................................................................................................................................................
.................................................................................................................................................................................................
................................................................................................................................................................................................. [1]

Fig. 3.1 shows the excretory system in a human male.



(a) Table 3.1 shows five functions of parts of the excretory system. Complete the table by:

• naming the part that carries out each of the functions
• using the letters from Fig. 3.1 to identify the structures named.

(a) Cystic fibrosis is an inherited disease. A person with cystic fibrosis produces mucus which is very sticky.
(i) The mucus affects the function of the cilia in the air passages.
Suggest what effects this will have on the person with this condition.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................[2]
(ii) The sticky mucus can also block the tube from the pancreas to the small intestine.
Explain why this affects the digestion of fats in a person with cystic fibrosis.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................[2]

(b) Cystic fibrosis is caused by a recessive allele.
State what is meant by the term allele.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................[1]

Fig. 4.1 shows a family tree where one child has cystic fibrosis.

(c) Using the symbols N for the dominant allele and n for the recessive allele:
(i) state the genotypes of the parents
father .............................................
mother .............................................[2]
(ii) state the genotype of child 2 ............................................[1]
(iii) state the possible genotypes of child 1 and child 3.
child 1 .............................................
child 3 .............................................[2]
(d) The parents have another child.
What is the probability (chance) that the child will have cystic fibrosis?
........................................................................................................................................[1]

(a) Fig. 5.1 shows a tomato seed.

[Image_1: Diagram of a tomato seed with labeling lines]

Label the three parts of the seed indicated by the label lines. Write your answers in the boxes on Fig. 5.1.

(b) Fig. 5.2 shows a section through a tomato fruit.

[Image_2: Diagram of a section through a tomato fruit showing a seed]

(i) The seeds inside the tomato fruit have a hard outer layer. Suggest why this layer is important to the seed.
........................................................
........................................................ [1]

(ii) Suggest how these seeds are dispersed successfully from the parent plant.
........................................................
........................................................
........................................................
........................................................ [2]

(c) One stage in the development of a flowering plant is the germination of seeds.

(i) Define the term development.
........................................................
........................................................
........................................................ [1]

(ii) Fig. 5.3 shows an experiment which was set up to investigate the conditions required for germination.

[Image_3: Diagram showing an experiment setup with flasks A, B, C, and D]

The seeds in flask A are in dry cotton wool. The seeds in flasks B, C, and D are in damp cotton wool.
Some of the seeds will germinate and some will not.
Complete Table 5.1 by stating whether the seeds in flasks A, B, C and D will germinate or not. Explain your answers.

[Table_1: Table 5.1 requiring input for seeds germination and explanation] [5]

Some students observed a number of organisms in a habitat. They saw that beetles eat plants, snakes eat frogs and frogs eat beetles.
(a) Write out a food chain linking these organisms. Write your answers in the boxes.

[1]
(b) Fig. 6.1 shows the population growth curve for the frog population over several years.
(i) The population curve shown in Fig. 6.1 has four phases.
Identify the four phases, P, Q, R and S, and write your answers in the boxes provided.
[Image_2: Fig. 6.1]
[4]
(ii) Using information from your food chain in part (a), and your knowledge of factors that affect population growth, suggest reasons for the shape of the curve in the region marked S on Fig. 6.1.
...................................................................................................................................................................
...................................................................................................................................................................
...................................................................................................................................................................
...................................................................................................................................................................
...................................................................................................................................................................
...................................................................................................................................................................
................................................................................................................. [3]

The list of words and phrases is about the relationships of organisms with one another and with their environment.
carnivore, decomposer, ecosystem, food chain, food web, herbivore, population, producer, pyramid of numbers, pyramid of biomass, trophic level
Table 7.1 shows a list of definitions of some of these words and phrases.
Match each definition with one word or phrase from the list. Write your answers in Table 7.1.
Each word may be used once, more than once or not at all.
Table 7.1
[Table_1]
definition | matching word or phrase
an animal that gets its energy by eating other animals
a network of interconnected food chains
an organism that makes its own organic nutrients by photosynthesis
the position of an organism in a food chain
an animal that gets its energy by eating plants
a group of organisms of one species, living in the same area at the same time
a unit containing all of the organisms and their environment, interacting together, in a given area
a diagram which shows the quantities of organisms involved in a set of feeding relationships

(a) Fig. 8.2 shows a plant.

Use the letters A, B, C, D, and E from Fig. 8.1 to show where these cells would be found on the plant shown in Fig. 8.2.

Write each of the letters in the appropriate box. One box will be left blank.
[Image_1: Fig. 8.1]
[Image_2: Fig. 8.2]
[5]

(b) Explain how the structures of cells A and E are related to their functions.
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
[4]

(a) Fig. 9.1 represents two liquids, A and B, separated by a partially permeable membrane.

A is pure water and B is a sugar solution.
In the human alimentary canal, water moves from the colon into the blood.
Use the information in Fig. 9.1 to explain the movement of water from the colon into the blood.

(b) The ratio of the surface area to the volume of a cell affects the rate of diffusion of a substance into the cell.
The results of an investigation on diffusion into a cube-shaped cell are shown in Table 9.1.
(i) Complete Table 9.1. One of the rows has been done for you.
[Table_1]
(ii) Suggest how surface area to volume ratio affects the efficiency of diffusion.

(c) Explain one way that the lungs of a mammal are adapted to increase the rate of diffusion of oxygen from the alveoli to the blood.